Normally, the air outlet(s) in an air conditioning system such as used in motor vehicles has a row of vanes that are mounted in a pivotal frame and are linked for pivotal movement in parallel relationship to provide variable direction flow in two mutually perpendicular directions (vertical and horizontal). And where it is desired to diffuse the exiting air for wider area coverage of the air jet and/or comfort reasons, it is common practice to add fixed diffuser vanes in the outlet that direct some of the air at intersecting angles with the flow from the first mentioned vanes. However, the fixed angle of the diffuser vanes is not suited to all the possible angles of the pivotal vanes and can as a result cause a significant loss in air velocity, a wide temperature differential across the air jet, and a coverage area that varies with the direction of the pivotal vanes. And these are all important considerations within the relatively small confines of a motor vehicle passenger compartment as compared with home, commercial and industrial space.